Position encoders are among a number of electro-mechanical transducers that may be used to sense a position of an object. Position encoders may be configured to sense an actual, or “absolute,” position of an object, as well as a “relative” position, or a displacement, of the object. Furthermore, a position encoder may comprise any of a wide variety of linear and angular, or “rotary,” position encoders. In some examples, position encoders may use contact-based sensing means to sense a position of an object by mechanically coupling the object to the position encoder, e.g., to a movable member or a rotating shaft of the position encoder, which may be mechanically coupled to a sensing element of the position encoder. In other examples, position encoders may employ a wide variety of contactless sensing means, such as optical, magnetic, capacitive, and inductive means, as some examples. Position encoders employing such contactless sensing means may be less susceptible to wear and may provide greater durability compared to contact-based position encoders.
As one example, a linear position encoder may sense a position of an object moving along a linear trajectory relative to the linear position encoder. For example, the linear position encoder may sense a position of an encoder “read-head” that is coupled to the object relative to an encoder track as the encoder read-head and the object move together along the encoder track. The position of the read-head relative to the encoder track may be sensed using mechanical, optical, magnetic, capacitive, or inductive means, as well as using other sensing means.
As another example, an angular, or rotary, position encoder may sense an angular position of an object that is rotating about an axis of rotation relative to the angular position encoder. For example, in the case of the angular position encoder employing magnetic sensing means, as described above, the angular position encoder may sense an angular position of a magnetic target that is coupled to the rotating object relative to one or more magnetic field sensors disposed within a base of the angular position encoder. The magnetic target may be disposed substantially at a center of the base so as to generate a uniform magnetic field which varies from the perspective of the one or more magnetic field sensors based on the angular position of the magnetic target relative to the sensors. In this example, the one or more magnetic field sensors may include magnetoresistive (MR) sensors, Hall-Effect sensors, or other magnetic sensors.